JP4402647B2 - Lane departure amount estimation device - Google Patents

Description

  The present invention relates to a lane departure amount estimation apparatus, and relates to a technique for quickly and accurately estimating a departure amount while adopting a simple configuration.

  As a device for improving the running safety of vehicles, ABS (Anti-lock Breaking System) for preventing wheel lock during braking and TCS (Traction Control System) for preventing wheel idling during acceleration are widely used. In addition, a vehicle attitude control device having a function of suppressing a side slip at the time of turning is also used in part. When a side slip occurs due to understeer or oversteer during turning, the vehicle deviates from a travel locus (usually a travel lane) intended by the driver. Therefore, in the vehicle attitude control device, at the stage of determining the departure from the travel lane, either the left or right wheel is braked by the independent braking device, or the steering assist torque by the power steering device is given, so that the vehicle Control is performed to return the vehicle to the traveling lane.

Various methods are known as methods for determining and predicting deviations from the driving lane of a vehicle. For example, the present applicant uses a steering control device (see Patent Document 1) or a ground load control device (see Patent Document 2) that calculates a deviation amount of a vehicle based on map data (road node coordinate data) of a navigation system. Proposed in the past. In these devices, the deviation amount is geometrically determined from the vehicle motion parameters obtained from various sensors (vehicle speed sensor, steering angle sensor, yaw rate sensor, G sensor, etc.) and the turning radius of the road calculated from the map data. A deviation is determined by calculating and comparing this with a predetermined threshold. Also, a lane departure warning device (see Patent Document 3) and a lane departure prevention device (see Patent Document 4) that captures the front of the vehicle with a CCD camera installed at the front of the vehicle body and predicts the departure of the vehicle based on the imaged data. ) Has also been proposed in the past. In these devices, deviations are predicted from vehicle motion parameters obtained from various sensors and the turning radius, yaw angle, etc. of the road obtained by image processing of the imaged data.
JP 2005-284441 A Japanese Patent Laid-Open No. 11-048737 JP 2004-038487 A JP 2004-284485 A

  Since the expensive navigation system is indispensable for the deviation determination methods of Patent Documents 1 and 2, it has been difficult to widely adopt from the viewpoint of apparatus cost. Further, since the navigation system is a system that guides the travel route, when the distance between the road nodes in the map data is set large on a mountain road with few intersections, the deviation amount cannot be calculated with high accuracy. On the other hand, the deviation prediction methods of Patent Documents 3 and 4 require an expensive CCD camera and the like, and the cost of the apparatus is high. In addition, the road shape cannot be accurately recognized during rainy weather, snowfall, backlighting, etc. There was a risk that deviation could not be predicted.

  The present invention has been made in view of the above situation, and an object of the present invention is to provide a lane departure amount estimation device that can quickly and accurately estimate a departure amount while adopting a simple configuration.

A lane departure amount estimation device according to a first aspect of the present invention is a lane departure amount estimation device mounted on a vehicle, and detects vehicle body speed detection means for detecting a vehicle body speed of the vehicle and a steering angle of a steering wheel. Steering angle detecting means; reference yaw rate calculating means for calculating a reference yaw rate of the vehicle based on the vehicle speed and the steering angle; actual yaw rate detecting means for detecting an actual yaw rate of the vehicle; the reference yaw rate and the actual yaw rate; A yaw rate difference integrating means for integrating a difference from the yaw rate over a predetermined time to obtain a yaw rate difference integrated value; an estimated deviation from the target travel locus of the vehicle; D; the vehicle speed; V; the predetermined time; t; Deviation amount estimation means for calculating the estimated deviation amount D by the following equation when the difference integral value is θd is provided.
D = V · t · θd

  According to a second aspect of the present invention, a lane departure amount estimation apparatus according to the first aspect further comprises tire slip angle estimation means for estimating a tire slip angle of a steering wheel, wherein the yaw rate difference is estimated. The integration means is characterized in that the integration is started when the value of the tire slip angle estimated by the tire slip angle estimation means exceeds a predetermined value.

A lane departure amount estimation device according to a third aspect of the invention is a lane departure amount estimation device mounted on a vehicle, based on steering angle detection means for detecting a steering angle of a steering wheel, and the steering angle. Target turning curvature calculating means for calculating the target turning curvature of the vehicle, body speed detecting means for detecting the vehicle speed of the vehicle, lateral acceleration detecting means for detecting the lateral acceleration of the vehicle, the vehicle speed and the lateral An actual turning curvature calculating means for calculating the actual turning curvature of the vehicle based on the acceleration; D, an estimated deviation from the target travel locus of the vehicle; V, the vehicle speed; t, the predetermined time, t, the target turning curvature. And a deviation amount estimating means for calculating the estimated deviation amount D by the following equation, where e is the difference between the actual turning curvature and the actual turning curvature.
D = V · t · e

  According to the lane departure amount estimation apparatus of the present invention, it is possible to quickly and accurately estimate a vehicle departure amount from a traveling lane using an existing device without using expensive equipment such as a navigation system and a CCD camera. Will be able to.

  Hereinafter, two embodiments of a lane departure amount estimation apparatus according to the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a plan view showing a device configuration of a vehicle according to the first embodiment, FIG. 2 is a block diagram showing a schematic configuration of a VSA-ECU according to the first embodiment, and FIG. 3 shows the configuration of the first embodiment. It is a figure which shows the two-wheeled vehicle model of the vehicle at the time of the cornering which concerns.

<Vehicle device configuration>
First, the device configuration of the vehicle will be described with reference to FIG. In the description, for the four wheels and members arranged corresponding thereto, that is, tires, wheel speed sensors, and the like, subscripts indicating front, rear, left, and right are attached to the reference numerals, for example, wheel 3fl (front left) ), Wheel 3fr (right front), wheel 3rl (left rear), wheel 3rr (right rear), and collectively referred to as wheel 3, for example.

  As shown in FIG. 1, a vehicle (passenger car in this embodiment) 1 includes four wheels 3 on which tires 2 are mounted. Each wheel 3 has a brake 4 and a wheel speed sensor (vehicle speed detection means). 5 and are decorated. In addition, the vehicle 1 controls an EPS (Electric Power Steering) 7 and an EPS 7 in addition to a VSA (Vehicle Stability Assist: Vehicle Behavior Stabilization Control System) -ECU (Electronic Control Unit) 6 in the vehicle interior. An EPS-ECU 8 is provided, a hydraulic unit 9 that supplies pressure oil to each brake 4, and an ENG-ECU 11 that controls the engine 10. The vehicle 1 includes a yaw rate sensor (actual yaw rate detection means) 12 that detects the actual yaw rate of the vehicle 1, a longitudinal G sensor 13 that detects the longitudinal acceleration of the vehicle 1, and a lateral G sensor that detects the lateral acceleration of the vehicle 1. 14 in the passenger compartment.

  Each of the VSA-ECU 6, EPS-ECU 8 and ENG-ECU 11 includes a microcomputer, a ROM, a RAM, a peripheral circuit, an input / output interface, various drivers, etc., and a communication line (in this embodiment, a CAN (Controller Area Network)). Further, the hydraulic unit 9 includes four systems such as an electric valve and a hydraulic circuit, and can supply pressure oil having different pressures to the brakes 4 of the respective wheels 3.

  The EPS 7 has as main components a steering gear 21 composed of a rack and a pinion (not shown), a steering shaft 23 with a steering wheel 22 attached to the rear end, and an EPS motor 24 that applies a steering assist force to the steering shaft 23. A steering angle sensor (steering angle detecting means) 25 for detecting the steering angle of the steering wheel 22 is attached to the steering shaft 23.

<Configuration of VSA-ECU>
Next, with reference to FIG. 2, the principal part structure of VSA-ECU6 of 1st Embodiment is demonstrated.
The VSA-ECU 6 of the first embodiment includes a vehicle body speed estimation unit 31, a standard yaw rate calculation unit (standard yaw rate calculation unit) 32, a slip angle estimation unit (tire slip angle estimation unit) 33, and a tire model setting unit 34. The front / rear / lateral G estimation unit 35, the road surface friction coefficient estimation unit 36, the estimation start command output unit 37, the lane departure amount estimation unit (yaw rate difference integration means, departure amount estimation means) 38, and the motion state determination unit 39 And a control signal output unit 40.

  The vehicle body speed estimation unit 31 calculates a vehicle body speed V of the vehicle 1 based on wheel speed detection signals (hereinafter simply referred to as wheel speeds) Wfl, Wfr, Wrl, Wrr input from the wheel speed sensor 5 of each wheel 3. To do. In addition, the tire slip angle α from the slip angle estimation unit 33 and the tire data from the tire model setting unit 34 are input to the vehicle body speed estimation unit 31 as correction information.

  The standard yaw rate calculation unit 32 is based on the estimated value of the vehicle body speed V input from the vehicle body speed estimation unit 31 and the steering angle detection signal (hereinafter simply referred to as a steering angle) δ input from the steering angle sensor 25. γN is calculated.

  The slip angle estimator 33 includes a vehicle speed V input from the vehicle speed estimator 31, a steering angle δ input from the steering angle sensor 25, and an actual yaw rate detection signal input from the yaw rate sensor 12 (hereinafter simply referred to as actual yaw rate). The tire slip angle α and the vehicle body slip angle β are calculated based on γ and the actual lateral acceleration detection signal LG (hereinafter simply referred to as the actual lateral acceleration) LG input from the lateral G sensor 14. In the case of the present embodiment, as shown in FIG. 3, a two-wheel model is used for estimating the tire slip angle α, and the slip angle estimating unit 33 uses the front wheel side tire slip angle αf as the tire slip angle α. And the rear wheel side tire slip angle αr.

  The tire model setting unit 34 includes a tire slip angle α input from the slip angle estimation unit 33, a longitudinal acceleration estimation value FGE and a lateral acceleration estimation value input from the longitudinal / lateral G estimation unit 35 and the road surface friction coefficient estimation unit 36, which will be described later. Based on the LGE and the road surface friction coefficient estimated value μ, a dynamic model of the tire 2 is set.

  The longitudinal / lateral G estimating unit 35 calculates the longitudinal acceleration estimated value FGE and the lateral acceleration estimated value LGE based on the tire slip angle α input from the slip angle estimating unit 33 and the tire data from the tire model setting unit 34. .

  The road surface friction coefficient estimator 36 includes an actual yaw rate γ input from the yaw rate sensor 12, an actual longitudinal acceleration detection signal (hereinafter simply referred to as an actual longitudinal acceleration) FG input from the longitudinal G sensor 13, and a lateral G Based on the actual lateral acceleration LG of the vehicle 1 input from the sensor 14, a road surface friction coefficient estimated value μ is calculated. The road surface friction coefficient estimator 36 receives the longitudinal acceleration estimated value FGE and the lateral acceleration estimated value LGE from the longitudinal / lateral G estimator 35 as correction information.

  The estimation start command output unit 37 is based on the vehicle body speed V input from the vehicle body speed estimation unit 31 and the road surface friction coefficient estimation value μ input from the road surface friction coefficient estimation unit 36. A process start command Sstart is output to the state determination unit 39.

  The lane departure amount estimation unit 38 is based on the vehicle body speed V input from the vehicle body speed estimation unit 31, the standard yaw rate γN input from the standard yaw rate calculation unit 32, and the actual yaw rate γ input from the yaw rate sensor 12. Is output to the control signal output unit 40.

  The motion state determination unit 39 calculates the front / rear slip angle difference αfr from the front and rear tire slip angles αf and αr input from the slip angle estimation unit 33, and then inputs the front / rear slip angle difference αfr and the steering angle sensor 25. The motion state Pm of the vehicle 1 is determined based on the steering angle δ, the road surface friction coefficient estimation value μ input from the road surface friction coefficient estimation unit 36, and the vehicle body speed V input from the vehicle body speed estimation unit 31, and this is determined as a control signal. Output to the output unit 40.

  Based on the estimated departure amount D input from the lane departure amount estimation unit 38 and the movement state Pm input from the movement state determination unit 39, the control signal output unit 40 controls the EPS-ECU 8 and the ENG to suppress the lane departure. -A control command is output to ECU11 and the hydraulic unit 9.

<< Operation of First Embodiment >>
When the vehicle 1 starts traveling, the VSA-ECU 6 starts the wheel speed Wfl, Wfr, Wrl, Wrr from the wheel speed sensor 5 of each wheel 3, the steering angle δ from the steering angle sensor 25, and the yaw rate sensor 12. The actual yaw rate γ, the actual longitudinal acceleration FG from the longitudinal G sensor 13 and the actual lateral acceleration LG from the lateral G sensor 14 are input, and the lane departure suppression control whose procedure is shown in the flowchart of FIG. 4 is performed at a predetermined control interval (for example, 10 ms).

<Start control>
In the VSA-ECU 6, the vehicle speed estimation unit 31, the slip angle estimation unit 33, and the road surface friction coefficient estimation unit 36 perform calculations in step S1 of FIG. 4, respectively, and the vehicle speed V, the tire slip angle α, and the vehicle body slip angle β are calculated. The road surface friction coefficient estimated value μ is calculated. In addition, the normative yaw rate calculation unit 32, the tire model setting unit 34, and the front / rear / lateral G estimation unit 35 also execute the various processes described above.

  Next, in the VSA-ECU 6, in step S2, the estimation start command output unit 37 determines whether or not the absolute value of the steering angle δ is larger than a predetermined estimation start determination threshold value δth (for example, 3 ° to 5 °). If this determination is No, the process returns to the start. In the determination in step S2, the estimation start command output unit 37 calculates an average value of the steering angle δ over a predetermined time (for example, 0.1 seconds) in order to remove instantaneous fluctuations caused by road kickback or the like. The absolute value is used for determination.

  When the driver steers the steering wheel 22 and the determination in step S2 is Yes, in the VSA-ECU 6, next in step S3, the estimation start command output unit 37 estimates the absolute value of the front wheel side tire slip angle αf to a predetermined value. It is determined whether or not it is larger than the start determination threshold value αfth. If this determination is No, the process returns to the start. In the case of the present embodiment, the value of the estimation start determination threshold value αfth is given by the estimation start determination threshold value map shown in FIG. 5 and is set to be larger as the estimated road surface friction coefficient estimated value μ is higher and smaller as the vehicle body speed V is higher. Yes. Also in the determination in step S3, the estimation start command output unit 37 calculates an average value of the front wheel side tire slip angle αf over a predetermined time (for example, 0.1 second) for the same reason as in the determination in step S2, The absolute value is used for determination.

  When the absolute value of the front wheel side tire slip angle αf exceeds the estimation start determination threshold value αfth and the determination in step S3 is also Yes, the VSA-ECU 6 processes the estimation start command output unit 37 to the lane departure amount estimation unit 38 in step S4. The start command Sstart is output, and the lane departure amount estimation unit 38 starts departure amount estimation processing whose procedure is shown in the flowchart of FIG.

<Deviation amount estimation processing>
When the departure amount estimation process is started, the lane departure amount estimation unit 38 determines whether or not there is steering by the driver in step S21 in FIG. 6 (whether or not the steering state in step S2 is continued). judge). If the determination in step S21 is Yes, the lane departure amount estimation unit 38 determines whether or not the counter steer state is set in step S22. If the determination in step S22 is also Yes, the lane departure amount estimation unit 38 determines whether or not the absolute value of the front wheel side tire slip angle αf is larger than the estimation start determination threshold value αfth in step S23. If the determination in step S23 is also Yes, the lane departure amount estimation unit 38 determines whether or not the oversteer state is further established in step S24.

  If any one of the determinations in steps S21 to S24 is No, the lane departure amount estimation unit 38 resets the timer counter T to 0 in step S25, and in step S26, the yaw rate difference Δγ and departure angle estimation which will be described later are estimated. The values θd and estimated deviation D are all reset to zero. The timer counter T has an initial value of 0, and is started at the start of the deviation amount estimation process.

  When all the determinations in steps S21 to S24 are Yes, the lane departure amount estimation unit 38 calculates the yaw rate difference Δγ by subtracting the actual yaw rate γ from the reference yaw rate γN in step S27. In step S28, the lane departure amount estimation unit 38 integrates the yaw rate difference Δγ to obtain the departure angle estimated value θd (n) of the vehicle 1 at the current time. That is, the lane departure amount estimation unit 38 adds the yaw rate difference Δγ to the previous value θd (n−1) of the departure angle estimation value of the initial value 0, and obtains the current value θd (n) of the departure angle estimation value.

When the current value θd (n) of the departure angle estimated value is obtained in step S28, the lane departure amount estimation unit 38 obtains the current value θd (n) of the departure angle estimated value, the vehicle body speed V, and the accumulated time t (that is, in step S29). And the value of the timer counter T), the estimated deviation D at the present time is calculated by the following equation (1), and the calculation result is output to the control signal output unit 40.
D = V · t · θd (n) (1)

  FIG. 7 (a) schematically shows a travel locus when the vehicle 1 is turning, and FIG. 7 (b) schematically shows a deviation amount estimation method according to expression (1). The estimated deviation amount D is obtained by multiplying the tangent (tan θd (n)) of the current value θd (n) of the estimated deviation angle value by the vehicle body speed V and the accumulated time t, and the value of θd (n) is compared. Therefore, the value θd (n) is calculated by multiplying the vehicle speed V and the accumulated time t as an approximate value. Thereby, the calculation of the estimated deviation amount D can be performed easily and in an extremely short time, and the control response speed is improved.

<Exercise state determination process>
If both the determinations in steps S2 and S3 in FIG. 4 are Yes, the VSA-ECU 6 outputs the process start command Sstart from the estimation start command output unit 37 to the motion state determination unit 39 in step S5, and the motion state The determination unit 39 starts an exercise state determination process whose procedure is shown in the flowchart of FIG.

When the motion state determination process is started, the motion state determination unit 39 calculates the absolute value of the value obtained by dividing the front wheel side tire slip angle αf from the front wheel side tire slip angle αf by the following equation (2) in step S31. Calculated as the difference αfr.
αfr = | αf−αr | (2)

  When the calculation of the front / rear slip angle difference αfr is completed, the motion state determination unit 39 determines in step S32 based on the front / rear slip angle difference αfr, the steering angle δ, the vehicle body speed V, and the road surface friction coefficient estimated value μ. The motion state Pm of the vehicle 1 is retrieved from the motion state determination map shown in FIG. As can be seen from FIG. 9, in the motion state determination map, the motion state Pm of the vehicle 1 changes from the grip turning region to the grip limit, understeer region, and drift-out region as the longitudinal slip angle difference αfr increases. The motion state determination map is normalized under the conditions of a predetermined speed (for example, V = 50 km / h) and a dry road surface (μ = 1), and when searching for the motion state Pm, the vehicle speed V and the road surface friction coefficient are obtained. Gain conversion is performed according to the estimated value μ.

  When the search for the exercise state Pm is completed in step S32, the exercise state determination unit 39 determines whether or not the exercise state Pm is in the grip turning region in step S33. If this determination is Yes, the exercise state Pm is determined in step S34. The state Pm is output to the control signal output unit 40 as P0. If the determination in step S33 is No, the exercise state determination unit 39 determines whether the exercise state P is at the grip limit in step S35. If this determination is Yes, the exercise state is determined in step S36. Pm is output to the control signal output unit 40 as P1. If the determination in step S35 is No, the exercise state determination unit 39 determines whether the exercise state P is in the understeer region in step S37. If this determination is Yes, the exercise state is determined in step S38. Pm is output to the control signal output unit 40 as P2. If the determination in step S37 is No, the exercise state determination unit 39 determines whether the exercise state P is in the drift-out region in step S39. If this determination is Yes, the exercise state determination unit 39 determines whether the exercise state P is in the drift-out region. The state Pm is output to the control signal output unit 40 as P3.

<Control signal output processing>
In the VSA-ECU 6, the control signal output unit 40 performs control signal output processing based on the estimated departure amount D input from the lane departure amount estimation unit 38 and the motion state Pm input from the motion state determination unit 39.

  That is, the control signal output unit 40 determines whether or not the estimated deviation amount D exceeds a predetermined deviation determination value Dth (for example, 1 m) in step S6 of FIG. 4, and if this determination is Yes, the process proceeds to step S7. move on. In this situation, since there is a high possibility that the vehicle 1 will go out of the course, the control signal output unit 40 sends a control signal to the hydraulic unit 9 and the ENG-ECU 11 so that understeer suppression and braking are performed together in step S7. Output. As a result, the driving force of the wheel 3 on the inside of the turn is reduced and understeer is suppressed, and at the same time, all the wheels 3 are braked and the output torque of the engine 10 is reduced accordingly. Improves.

  If the determination in step S6 is No, the control signal output unit 40 determines whether or not the motion state Pm is P3 (drift-out region) in step S8, and if this determination is Yes, the step Proceed to S7. In this situation, since the vehicle 1 is in a drift-out state, understeer suppression and braking are performed in the same manner as when the estimated departure amount D exceeds the departure determination value Dth.

  If the determination in step S8 is No, the control signal output unit 40 determines whether or not the motion state Pm is P2 (understeer region) in step S9. If this determination is Yes, step S10 is performed. Proceed to In step S10, the control signal output unit 40 outputs a control signal to the hydraulic unit 9 and the ENG-ECU 11 to suppress understeer. As a result, the driving force of the wheel 3 on the inside of the turn is reduced and the output torque of the engine 10 is also reduced, the understeer is suppressed, and the vehicle 1 is less likely to deviate from the travel lane.

  If the determination in step S9 is No, the control signal output unit 40 determines whether or not the exercise state Pm is P1 (grip limit) in step S11. If this determination is Yes, step S12. Proceed to In step S12, the control signal output unit 40 outputs a control signal to the EPS-ECU 8 in order to suppress steering assist by the EPS 7. As a result, the steering assist force generated by the EPS motor 24 decreases, and the motion state P of the vehicle 1 shifts from the grip limit to the grip turning region.

[Second Embodiment]
FIG. 10 is a block diagram showing a schematic configuration of a VSA-ECU according to the second embodiment. In the second embodiment, the device configuration of the vehicle is the same as that of the first embodiment described above.

<Configuration of VSA-ECU>
Next, with reference to FIG. 10, the principal part structure of VSA-ECU6 of 2nd Embodiment is demonstrated. In addition, about VSA-ECU6, the same code | symbol is attached | subjected to the process parts which perform the process similar to 1st Embodiment, such as a vehicle body speed estimation part and a slip angle estimation part, and the overlapping description is abbreviate | omitted.

  The VSA-ECU 6 of the second embodiment includes a vehicle body speed estimation unit 31, a target turning curvature calculation unit (target turning curvature calculation unit) 41, an actual turning curvature calculation unit (actual turning curvature calculation unit) 42, and a slip angle estimation. Unit 33, tire model setting unit 34, front / rear / lateral G estimation unit 35, road surface friction coefficient estimation unit 36, estimation start command output unit 37, lane departure amount estimation unit 38, and motion state determination unit 39 And a control signal output unit 40.

  The target turning curvature calculation unit 41 calculates a target turning curvature ρ based on the steering angle δ from the steering angle sensor 25 and the tire slip angle α input from the slip angle estimation unit 33 input from the front / rear / lateral G estimation unit 35. .

  The actual turning curvature calculation unit 42 calculates the actual turning curvature R based on the vehicle body speed V input from the vehicle body speed estimation unit 31 and the actual lateral acceleration LG of the vehicle 1 input from the lateral G sensor 14.

<< Operation of Second Embodiment >>
When the vehicle 1 starts traveling, the VSA-ECU 6 starts the wheel speed Wfl, Wfr, Wrl, Wrr from the wheel speed sensor 5 of each wheel 3, the steering angle δ from the steering angle sensor 25, and the yaw rate sensor 12. The actual yaw rate γ, the actual longitudinal acceleration FG from the longitudinal G sensor 13 and the actual lateral acceleration LG from the lateral G sensor 14 are input, and the lane departure suppression control whose procedure is shown in the flowchart of FIG. 11 is performed at a predetermined control interval (for example, 10 ms).

<Start control>
In the VSA-ECU 6, the vehicle body speed estimation unit 31, the slip angle estimation unit 33, and the road surface friction coefficient estimation unit 36 perform calculations in step S51 of FIG. 11, respectively, and the vehicle body speed V, the tire slip angle α, and the vehicle body slip angle β are calculated. The road surface friction coefficient estimated value μ is calculated. In addition, the tire model setting unit 34 and the front / rear / lateral G estimation unit 35 also execute the various processes described above.

  Next, in the VSA-ECU 6, in step S52, the estimation start command output unit 37 determines whether or not the absolute value of the steering angle δ is greater than a predetermined estimation start determination threshold value δth (for example, 3 ° to 5 °). If this determination is No, the process returns to the start. In the determination in step S52, the estimation start command output unit 37 calculates an average value of the steering angle δ over a predetermined time (for example, 0.1 second) in order to remove instantaneous fluctuations caused by road kickback or the like. The absolute value is used for determination.

  When the driver steers the steering wheel 22 and the determination in step S52 is YES, in the VSA-ECU 6, next in step S53, the estimation start command output unit 37 estimates the absolute value of the front wheel side tire slip angle αf to a predetermined value. It is determined whether or not it is larger than the start determination threshold value αfth. If this determination is No, the process returns to the start. In the case of the present embodiment, the value of the estimation start determination threshold value αfth is given by the estimation start determination threshold value map shown in FIG. 5 and is set to be larger as the estimated road surface friction coefficient estimated value μ is higher and smaller as the vehicle body speed V is higher. Yes. Also in the determination in step S53, the estimation start command output unit 37 calculates an average value of the front wheel side tire slip angle αf over a predetermined time (for example, 0.1 second) for the same reason as in the determination in step S52. The absolute value is used for determination.

  When the absolute value of the front wheel side tire slip angle αf exceeds the estimation start determination threshold value αfth and the determination in step S53 is also Yes, the VSA-ECU 6 processes the estimation start command output unit 37 to the lane departure amount estimation unit 38 in step S54. The start command Sstart is output, and the lane departure amount estimation unit 38 starts a correction coefficient calculation process whose procedure is shown in the flowchart of FIG.

<Correction coefficient calculation process>
When the correction coefficient calculation process is started, the lane departure amount estimation unit 38 is based on the vehicle body speed V input from the vehicle body speed estimation unit 31 and the steering angle δ input from the steering angle sensor 25 in step S71 of FIG. A required lateral force (necessary grip force) FLδv required for the vehicle 1 to turn is estimated by the following equation (3).
FLδv = (δw−αfr) / L _WB · V ² (3)
Here, .delta.w is actual steering angle of the front wheels obtained by the map, not shown, from δ steering angle,? FR is around the slip angle difference? FR determined by the aforementioned formula (2), L _WB is the vehicle 1 hole base It is.

  Next, the lane departure amount estimation unit 38 determines whether or not the required lateral force FLδv is smaller than the road surface friction coefficient estimation value μ input from the road surface friction coefficient estimation unit 36 in step S72. Since this is not a condition for obtaining correction coefficients K1 and K2, which will be described later, the correction coefficient setting flag Fcc, which will be described later, is set to 0 in step S73 and the process returns to the start.

  If the requested lateral force FLδv is equal to or greater than the road surface friction coefficient estimated value μ and the determination in step S72 is Yes, the lane departure amount estimating unit 38 determines that the actual lateral acceleration LG is in a predetermined range (eg, (0.1 <LG) in step S74. ≦ 0.4) and (0.4 <LG ≦ 0.8) or (0.8 <LG ≦ 1.0)) (ie, the turning situation has not changed) If this determination is No, the correction coefficient setting flag Fcc is set to 0 in step S73 and the process returns to the start.

  When the actual lateral acceleration LG remains in the predetermined range and the determination in step S74 is Yes, the lane departure amount estimation unit 38 determines whether or not the first calculation flag Fc1 having an initial value 0 is 1 in step S75. To do. Since this determination is No for the first time, the lane departure amount estimation unit 38 determines whether or not the second calculation flag Fc2 having an initial value of 0 is 1 in step S76.

  Since the determination in step S76 is also No for the first time, the lane departure amount estimation unit 38 determines whether or not the value of the first countdown timer Tcd1 having a predetermined initial value (for example, 2s to 5s) is 0 in step S77. While this determination is No, in step S78, the first average value FLμ of the vehicle body lateral force FLμ obtained from the first average value FLδv (n) of the requested lateral force FLδv and the estimated friction coefficient μ. (N) is calculated, and the first countdown timer Tcd1 is subtracted in step S79.

When the value of the first countdown timer Tcd1 is 0 and the determination in step S77 is Yes, the lane departure amount estimation unit 38 determines the first average value FLδv (n) of the requested lateral force FLδv and the first average value of the vehicle body lateral force FLμ. In order to express the relationship with FLμ (n) by an arithmetic expression, after obtaining the following expression (4) in step S80, the first calculation flag Fc1 is set to 1 in step S81.
FLδv (n) = K1 · FLμ (n) + K2 (4)
Here, K1 and K2 are correction coefficients for correcting errors due to suspension system (bushing) deflection, tire deflection, vehicle body deflection, steering system loss, detection errors of various sensors, and the like.

  When the first calculation flag Fc1 is 1 and the determination in step S76 is Yes, the lane departure amount estimation unit 38 determines that the value of the second countdown timer Tcd2 having a predetermined initial value (for example, 2s to 5s) is 0 in step S82. While this determination is No, in step S83, the vehicle body lateral force FLμ obtained from the second average value FLδv (n + 1) of the requested lateral force FLδv and the estimated friction coefficient μ is determined. A second average value FLμ (n + 1) is calculated, and the second countdown timer Tcd2 is subtracted in step S84.

When the value of the second countdown timer Tcd2 is 0 and the determination in step S82 is Yes, the lane departure amount estimation unit 38 determines the second average value FLδv (n + 1) of the requested lateral force FLδv and the second average value of the vehicle body lateral force FLμ. In order to express the relationship with FLμ (n + 1) by an arithmetic expression, after obtaining the following expression (5) in step S85, the second calculation flag Fc2 is set to 1 in step S86.
FLδv (n + 1) = K1 · FLμ (n + 1) + K2 (5)

  When the second calculation flag Fc2 is 1 and the determination in step S75 is Yes, the lane departure amount estimation unit 38 calculates correction coefficients K1 and K2 from equations (4) and (5) in step S87, and in step S88, 1, the second countdown timers Tcd1 and Tcd2 are reset, and the correction coefficient setting flag Fcc is set to 1 in step S89.

<Deviation amount estimation processing>
When the departure amount estimation process is started, the lane departure amount estimation unit 38 starts the departure amount estimation process whose procedure is shown in the flowchart of FIG. 13 in parallel with the correction coefficient calculation processing, and sets the timer counter T with an initial value of 0. to start.

  When the departure amount estimation process is started, the lane departure amount estimation unit 38 first determines whether or not the correction coefficient setting flag Fcc is 1 in step S91 of FIG. Since the timer counter T is reset in step S92, the process returns to the start.

  When the correction coefficient setting flag Fcc is 1 and the determination in step S91 is Yes, the lane departure amount estimation unit 38 determines in step S93 whether the absolute value | ΔV | of the vehicle speed change rate ΔV is smaller than a predetermined threshold value ΔVth. (I.e., whether or not the vehicle is in a constant speed state) is determined, and if this determination is No, the departure determination is still impossible, so the timer counter T is reset in step S92 and the process returns to the start.

  When the vehicle 1 is in the constant speed state and the determination in step S93 is Yes, the lane departure amount estimation unit 38 determines in step S94 the road surface friction coefficient estimated value K1 · K1 in which the required lateral force FLδv is corrected by the correction coefficients K1 and K2. It is determined whether it is larger than μ + K2. When this determination is No (that is, when it is expected that no side skid of the tire will occur), the lane departure amount estimation unit 38 resets the timer counter T in step S92 and then returns to the start.

When all the determinations at steps S91, S93, and S94 are Yes, the lane departure amount estimation unit 38 calculates the target turning radius ρ by the following equation (6) at step S95, and the actual turning by the following equation (7) at step S96. The radius R is calculated, and further, in step S97, the difference e between the target turning curvature and the actual turning curvature is calculated by the following equation (8).
ρ = L _WB / (δw−αfr) (6)
R = V ² / LG (7)
e = 1 / ρ−1 / R (8)

When the difference e between the target turning curvature and the actual turning curvature is obtained in step S97, the lane departure amount estimation unit 38, in step S98, the difference e between the target turning curvature and the actual turning curvature, the vehicle speed V, and the accumulated time t ( That is, using the timer counter T), the estimated deviation D at the present time is calculated by the following equation (9), and the calculation result is output to the control signal output unit 40.
D = V · t · e (9)

  FIG. 14 schematically shows a travel locus when the vehicle 1 is turning. Also in the second embodiment, the calculation of the estimated deviation amount D can be performed easily and in an extremely short time, and the control response speed is improved.

<Exercise state determination process>
If the determinations in steps S2 and S3 in FIG. 11 are both Yes, the VSA-ECU 6 outputs the process start command Sstart from the estimation start command output unit 37 to the motion state determination unit 39 in step S5, and the motion state The determination unit 39 starts an exercise state determination process whose procedure is shown in the flowchart of FIG.

  When the motion state determination process is started, the motion state determination unit 39 slips the absolute value of the value obtained by dividing the front wheel side tire slip angle αf from the front wheel side tire slip angle αf by the above-described equation (2) in step S101. Calculated as the angular difference αfr.

  When the calculation of the front / rear slip angle difference αfr is completed, the motion state determination unit 39 determines in step S102 based on the front / rear slip angle difference αfr, the steering angle δ, the vehicle body speed V, and the road surface friction coefficient estimated value μ. The motion state Pm of the vehicle 1 is retrieved from the motion state determination map shown in FIG.

  When the search for the exercise state Pm is completed in step S102, the exercise state determination unit 39 determines whether or not the exercise state Pm is in the grip turning area in step S103, and if this determination is Yes, exercise in step S104. The state Pm is output to the control signal output unit 40 as P0. If the determination in step S103 is No, the exercise state determination unit 39 determines whether the exercise state P is at the grip limit in step S105. If this determination is Yes, the exercise state is determined in step S106. Pm is output to the control signal output unit 40 as P1. If the determination in step S105 is No, the exercise state determination unit 39 determines whether or not the exercise state P is in the understeer region in step S107. If this determination is Yes, the exercise state is determined in step S108. Pm is output to the control signal output unit 40 as P2. If the determination in step S107 is No, the exercise state determination unit 39 determines whether the exercise state P is in the drift-out region in step S109. If this determination is Yes, the exercise state determination unit 39 determines whether the exercise state P is in the drift-out region. The state Pm is output to the control signal output unit 40 as P3.

<Control signal output processing>
In the VSA-ECU 6, the control signal output unit 40 performs control signal output processing based on the estimated departure amount D input from the lane departure amount estimation unit 38 and the motion state Pm input from the motion state determination unit 39.

  That is, the control signal output unit 40 determines whether or not the estimated deviation D exceeds a predetermined deviation determination value Dth (for example, 1 m) in step S56 of FIG. 11, and if this determination is Yes, the control signal output unit 40 proceeds to step S57. move on. In this situation, since there is a high possibility that the vehicle 1 will go out of the course, the control signal output unit 40 sends a control signal to the hydraulic unit 9 and the ENG-ECU 11 so that understeer suppression and braking are performed together in step S57. Output. As a result, the driving force of the wheel 3 on the inside of the turn is reduced and understeer is suppressed, and at the same time, all the wheels 3 are braked and the output torque of the engine 10 is reduced accordingly. Improves.

  If the determination in step S56 is No, the control signal output unit 40 determines whether or not the motion state Pm is P3 (drift out region) in step S58, and if this determination is Yes, the step Proceed to S57. In this situation, since the vehicle 1 is in a drift-out state, understeer suppression and braking are performed in the same manner as when the estimated departure amount D exceeds the departure determination value Dth.

  If the determination in step S58 is No, the control signal output unit 40 determines in step S59 whether or not the motion state Pm is P2 (understeer region). If this determination is Yes, step S60 is performed. Proceed to In step S60, the control signal output unit 40 outputs a control signal to the hydraulic unit 9 and the ENG-ECU 11 so as to suppress understeer. As a result, the driving force of the wheel 3 on the inside of the turn is reduced and the output torque of the engine 10 is also reduced, the understeer is suppressed, and the vehicle 1 is less likely to deviate from the travel lane.

  If the determination in step S59 is No, the control signal output unit 40 determines in step S61 whether or not the exercise state Pm is P1 (grip limit). If this determination is Yes, step S62 is performed. Proceed to In step S <b> 62, the control signal output unit 40 outputs a control signal to the EPS-ECU 8 in order to suppress steering assist by the EPS 7. As a result, the steering assist force generated by the EPS motor 24 decreases, and the motion state P of the vehicle 1 shifts from the grip limit to the grip turning region.

  In both the above-described embodiments, by adopting such a configuration, the vehicle from the traveling lane is output by the output of the existing sensors provided in the vehicle attitude control device without using expensive equipment such as a navigation system and a CCD camera. The deviation amount can be estimated quickly and with high accuracy.

  This is the end of the description of specific embodiments. However, aspects of the present invention are not limited to these embodiments. For example, in both of the above embodiments, the VSA-ECU performs moment control, braking control, and steering control based on the estimated deviation amount and the motion state of the vehicle. A warning may be given. In addition, the specific configuration of the vehicle, the specific procedure of the control, and the like can be appropriately changed without departing from the gist of the present invention.

It is a top view which shows the apparatus structure of the vehicle which concerns on 1st Embodiment. It is a block diagram which shows schematic structure of VSA-ECU which concerns on 1st Embodiment. It is a figure which shows the two-wheeled vehicle model of the vehicle at the time of turning driving | running | working which concerns on 1st Embodiment. It is a flowchart which shows the procedure of the lane departure suppression control which concerns on 1st Embodiment. It is an estimation start determination threshold value map which concerns on 1st Embodiment. It is a flowchart which shows the procedure of the deviation amount estimation process which concerns on 1st Embodiment. It is a schematic diagram which shows the travel locus | trajectory at the time of turning of the vehicle which concerns on 1st Embodiment, and the estimation method of deviation | deviation amount. It is a flowchart which shows the procedure of the exercise state determination process which concerns on 1st Embodiment. 3 is an exercise state determination map according to the first embodiment. It is a block diagram which shows schematic structure of VSA-ECU which concerns on 2nd Embodiment. It is a flowchart which shows the procedure of the lane departure suppression control which concerns on 2nd Embodiment. It is a flowchart which shows the procedure of the correction coefficient calculation process which concerns on 2nd Embodiment. It is a flowchart which shows the procedure of the deviation amount estimation process which concerns on 2nd Embodiment. It is a schematic diagram which shows the driving | running locus | trajectory at the time of turning of the vehicle which concerns on 2nd Embodiment, and the estimation method of deviation | deviation amount. It is a flowchart which shows the procedure of the exercise state determination process which concerns on 2nd Embodiment.

Explanation of symbols

1 vehicle 5 wheel speed sensor (body speed detection means)
6 VSA-ECU (lane departure estimation device)
12 Yaw rate sensor (actual yaw rate detection means)
13 Front / rear G sensor 14 Lateral G sensor (lateral acceleration detection means)
25 Steering angle sensor (steering angle detection means)
31 Vehicle speed estimation unit (vehicle speed estimation means)
32 normative yaw rate calculation unit (normative yaw rate calculation means)
33 Slip angle estimation unit (tire slip angle estimation means)
38 Lane deviation estimation unit (yaw rate difference integration means, deviation estimation means)
41 Target turning curvature calculation unit (target turning curvature calculation means)
42 Actual turning curvature calculation unit (actual turning curvature calculation means)

Claims (3)

A lane departure estimation device mounted on a vehicle,
Vehicle body speed detecting means for detecting the vehicle body speed of the vehicle;
Steering angle detection means for detecting the steering angle of the steering wheel;
A reference yaw rate calculating means for calculating a reference yaw rate of the vehicle based on the vehicle speed and the steering angle;
An actual yaw rate detecting means for detecting an actual yaw rate of the vehicle;
A yaw rate difference integrating means for integrating a difference between the reference yaw rate and the actual yaw rate over a predetermined time to obtain a yaw rate difference integrated value;
Deviation amount estimation that calculates the estimated deviation amount D by the following equation, where D is the estimated deviation amount from the target travel locus of the vehicle, V is the vehicle speed, t is the predetermined time, and θd is the integral value of the yaw rate difference. A lane departure amount estimation apparatus comprising: means for determining a lane departure amount;
D = V · t · θd Tire slip angle estimating means for estimating the tire slip angle of the steered wheel;
2. The lane departure amount estimation according to claim 1, wherein the yaw rate difference integrating means starts the integration when the value of the tire slip angle estimated by the tire slip angle estimating means exceeds a predetermined value. apparatus. A lane departure estimation device mounted on a vehicle,
Steering angle detection means for detecting the steering angle of the steering wheel;
A target turning curvature calculating means for calculating a target turning curvature of the vehicle based on the steering angle;
Vehicle body speed detecting means for detecting the vehicle body speed of the vehicle;
Lateral acceleration detecting means for detecting lateral acceleration of the vehicle;
An actual turning curvature calculating means for calculating an actual turning curvature of the vehicle based on the vehicle body speed and the lateral acceleration;
When the estimated deviation from the target travel locus of the vehicle is D, the vehicle speed is V, the predetermined time is t, and the difference between the target turning curvature and the actual turning curvature is e, the estimated deviation D is reduced. A lane departure amount estimation apparatus comprising: a departure amount estimation means for calculating by a formula.
D = V · t · e

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